Manipulation of fluids, fluid components and reactions in microfluidic systems

Abstract

Microfluidic structures and methods for manipulating fluids, fluid components, and reactions are provided. In one aspect, such structures and methods can allow production of droplets of a precise volume, which can be stored/maintained at precise regions of the device. In another aspect, microfluidic structures and methods described herein are designed for containing and positioning components in an arrangement such that the components can be manipulated and then tracked even after manipulation. For example, cells may be constrained in an arrangement in microfluidic structures described herein to facilitate tracking during their growth and/or after they multiply.

What is claimed is: 
     
       1. A method for partitioning a fluid, comprising the steps of:
 (a) providing a microfluidic network comprising a first fluid channel and a second fluid channel, wherein hydrodynamic resistance in the second fluid channel is lower than hydrodynamic resistance in the first fluid channel and wherein the first fluid channel and the second fluid channel are in fluid communication with a first region; 
 (b) flowing a first fluid through the first fluid channel, the first region, and the second fluid channel, wherein the first fluid causes hydrodynamic resistance in the second fluid channel to be higher than hydrodynamic resistance in the first fluid channel; and 
 (c) flowing a second fluid in the first fluid channel, wherein the second fluid is immiscible with the first fluid, and wherein the second fluid bypasses the first region, thereby partitioning a portion of the first fluid in the first region. 
 
     
     
       2. The method of  claim 1 , further comprising the steps of:
 (d) flowing a third fluid through the first fluid channel, wherein the third fluid contacts the portion of the first fluid in the first region. 
 
     
     
       3. The method of  claim 2 , wherein:
 the first fluid and the third fluid do not coalesce. 
 
     
     
       4. The method of  claim 2 , wherein:
 the first fluid comprises a first component species and the third fluid comprises a second component species. 
 
     
     
       5. The method of  claim 4 , wherein:
 the first component species in the first region causes, at least in part, the higher hydrodynamic resistance in the second fluid channel relative to the first fluid channel. 
 
     
     
       6. The method of  claim 4 , wherein:
 the first component species comprises a nucleic acid, a protein, a bead, or a cell. 
 
     
     
       7. The method of  claim 4 , wherein:
 the second component species comprises a binding partner to the first component species. 
 
     
     
       8. The method of  claim 1 , wherein:
 after the first region, the first fluid flows through a first fluid path, a second region, and a third fluid path that comprises a hydrodynamic resistance that is lower relative to that of the first fluid path, wherein the first fluid in the second region changes the hydrodynamic resistance in the third fluid path to be higher relative to that of the first fluid path and causes the second fluid to bypass the second region thereby partitioning a portion of the first fluid in the second region. 
 
     
     
       9. The method of  claim 2 , wherein:
 after the first region, the third fluid flows through a first fluid path, a second region, and a third fluid path that comprises a hydrodynamic resistance that is lower relative to that of the first fluid path, wherein the third fluid in the second region changes the hydrodynamic resistance in the third fluid path to be higher relative to that of the first fluid path. 
 
     
     
       10. The method of  claim 9 , wherein:
 the first region and the second region are fluidicly coupled to each other via the first fluid path. 
 
     
     
       11. The method of  claim 1 , wherein:
 the portion of the first fluid forms a droplet. 
 
     
     
       12. The method of  claim 11 , wherein:
 the formation of the droplet does not require the use of a surfactant.